Final Report Summary - QOM (Quantum Optomechanics: quantum foundations and quantum information on the micro- and nanoscale)
Quantum optomechanics has now emerged as a new, thriving field of research at the interface between quantum optics, quantum information and solid-state physics. It allows access to a new parameter regime of experimental physics with a plethora of applications: from novel on-chip devices for silicon photonics over hybrid architectures for quantum information processing to fundamental tests at the interface between quantum physics and gravity. Research in the ERC project “Quantum Optomechanics (QOM)” has contributed several milestone achievements to the field, including the first demonstration of the strong coupling regime between an optical cavity field and a micromechanical mirror and the first demonstration of laser-cooling a micromechanical device into its quantum ground state of motion, which are important pre-conditions to achieve full quantum control over mechanical devices, as well as the first demonstration of “cooling by measurement” through the concept of pulsed quantum optomechanics, which is a new approach to realize quantum non-demolition measurements of massive objects. The investigation of optomechanical properties of optical coatings has led to the development of a new technology of substrate-transferred crystalline coatings, which has been applied to significantly reduce thermal noise in optical interferometry. This has resulted in founding of the high-tech start-up company "Crystalline Mirror Solutions". Finally, we have proposed several experiments involving massive mechanical resonators that allow to test the interplay between quantum physics and gravity, either by testing so-called “collapse theories” that have been suggested as possible variants of quantum theory to solve the quantum measurement problem, or by testing specific theories of quantum gravity in table-top quantum optics experiments. This opens up an exciting research direction in fundamental physics for the next generation of mechanical quantum devices.